Field of the Invention and Related Art
The present invention relates to a manufacturing method for an ink jet recording head and the ink jet recording head treated with a water repellent in peripheral portions of discharge ports.
Among various recording methods currently known, the so-called ink jet recording method which allows the high speed recording is a quite effective recording method.
An ink jet recording head used in the ink jet recording method comprises a substrate on which energy generating elements having a heating resistor and a pair of electrodes electrically connected to the resistor are provided, and a grooved ceiling plate provided with grooves constituting liquid channels and discharge ports corresponding to energy generating elements, and a common liquid chamber for supplying the ink to the liquid channels by connection with the substrate. And the common liquid chamber has an ink supply port through which the ink is supplied.
In the recording head with such a constitution, physical properties (physical characteristics) on the surfaces of a plate member or the substrate and the ceiling plate constituting the discharge ports are significantly important in discharging the ink through the discharge ports stably at all times. That is, if liquid remaining may occur in a part of discharge port peripheries owing to the ink passing around or sticking to external surfaces (peripheries) of the discharge ports, there are some cases that the ink flying direction may be deviated from a normal predetermined direction, under the influence of remaining ink, when the ink is discharged from the discharge ports, and further, it is apprehended that its flying direction may be disordered for each discharge due to instability of liquid remaining state. Therefore, an excellent recording can not be obtained because the stable ink discharge state can not be maintained.
Also, if entire external surfaces around the discharge ports are covered with the ink film, the so-called splash phenomenon may arise, causing the scattering of discharged ink, so that the stable recording can not be performed. If ink remaining becomes large over the external surface of orifice or stagnant ink may fix, the recording head may result in inoperable state in which the ink can not be discharged.
This tendency may arise quite remarkably, when the high resolution recording is made with an increased nozzle density, or the driving is performed with a high frequency, i.e., when the high speed recording is tried, whereby a large problem may arise in improving the performance of the recording head.
In order to resolve the above problem that if ink liquid remaining occurs in peripheries of discharge ports, the stable discharge can not be performed, various proposals have been made heretofore in which a water-repellent layer 20 treated with the so-called water repellent is formed at least in peripheries of discharge ports, as disclosed for example in Japanese Laid-Open Patent Application No. 56-89569, Japanese Patent Publication No. 62-55154, Japanese Laid-Open Patent Application No.2-153744, and so on. As the water repellent useful in this water-repellent treatment, a variety of kinds such as silicone polymer or oligomer and fluorine polymer or oligomer can be cited.
By the way, the water-repellent layer 20 formed in the ink jet recording head must have an excellent water-repellent ability as well as a sufficient durability, for practical purposes.
Conventionally, in the ink jet recording method, a recovery operation of wiping a discharge port formation face with a cleaning blade is made to wipe away the ink adhering to the discharge port formation face further completely. Accordingly, the water-repellent layer is required to have an adhesiveness sufficient not to be peeled away or an abrasion resistance enough not to break the water-repellent layer even if rubbed out by the cleaning blade. If such a durability is insufficient, the water-repellent layer may be gradually peeled away or dropped off during the use of the head, even if the effect may be exhibited at the initial time of use, so that the stable ink discharge state can not be maintained.
In connection with the durability necessary for such ink jet recording head, there were some cases in which the water-repellent layer formed of a conventional water repellent might be not sufficient.
For example, specifically, when a water repellent which is relatively soft in hardness is used to make the adhesiveness with the discharge port formation face more excellent, the water repellent may be sometimes scratched off in a long-term use. In this case, such scratched water repellent will enter into discharge ports. In such a state, the meniscus position may be displaced, thereby causing a deviation of ink discharge direction, and yielding a deflection in the ink flying direction, so that the recording quality may be degraded. However, when the water-repellent layer is made of a water repellent having a high wiping durability and a very great hardness, there were some cases in which cracks or exfoliations might be caused by to the impact causes by the blade being brought into contact with the discharge port face.
Also, when a member surrounding the discharge ports is made of a plurality of different materials, it is requisite to form the water-repellent layer having a good adhesiveness with any of those materials, but no conventional water repellents meet that requirement sufficiently.
On the other hand, as previously described, in the ink jet head using the grooved ceiling plate in which the common liquid chamber, liquid channels, and a discharge port formation member are integrally formed, its grooved ceiling plate is made by molding, and thus is formed of one material. In this way, even though it is formed of one material, its material often must be selected from limited materials, owing to moldability or ink wetted property (wettability). Generally, a material such as polysulfone, polyether-sulfone-polyester or polyacetal is used, but such molding material may sometimes have insufficient adhesion with the water repellent, so that there was a problem that the water-repellent layer might be peeled away.
As one method in view of improving such an adhesiveness of the water repellent, a proposal has been made in which a predetermined pretreatment is applied for a water-repellent surface, for example.
For example, in Japanese Laid-Open Patent Application No. 61-141565, one method has been proposed in which ozonization is applied for the water-repellent surface, and then the water-repellent layer is provided. However, the connection between ozonized layer and water-repellent layer is not sufficient for the durability required for an ink jet recording head which performs the wiping with a cleaning blade.
Also, in Japanese Laid-Open Patent Application No. 61-291148, one method has been proposed in which a fluorine coating is made after treating the water-repellent surface by the use of a silane coupling agent. However, the durability against the wiping was insufficient because the silane coupling agent might not bond well strongly to the water-repellent surface. That is, a conventional pretreatment process could not cope with the improvement of water-repellent layer characteristics required for the ink jet recording head.
By the way, in the ink jet recording head which is made using the grooved ceiling plate in which a grooved substrate of common liquid chamber and liquid channels and a discharge port formation member are integrally formed, the present applicant has adopted a technology of forming discharge ports by using a laser beam.
That is, the machining of discharge ports with a pulsed laser beam is performed in such a way as to apply the laser beam from a back side of discharge port formation member (orifice plate) after treating the discharge port formation face with the water repellent. When the discharge ports are formed on the orifice plate using the pulsed laser beam, it has been found that there is a phenomenon that byproducts may be attached to the neighborhood of discharge ports during the laser beam machining, in examining a manufacturing method of the ink jet recording method.
When some byproducts with the laser beam machining are attached or deposited in the neighborhood of discharge ports, as above described, the condition of discharging the ink did not satisfy the required characteristics sufficiently. That is, if such byproducts are deposited on the water-repellent surface in the neighborhood of discharge ports, causing the deposited site to be in a state of hydrophilic property, such as phenomenon that the ink is attracted to its hydrophilic area can be seen in discharging the ink, so that the flying direction of liquid droplets are rendered unstable, thereby sometimes degrading the print quality.